acid test vs appraisal

acid test and appraisal both are nouns.

Word	Noun	Adjective	Verb	Adverb
acid test	Yes	No	No	No
appraisal	Yes	No	No	No

As nouns, appraisal is a hypernym of acid test; that is, appraisal is a word with a broader meaning than acid test:

acid test: a rigorous or crucial appraisal
appraisal: the classification of someone or something with respect to its worth

Other hypernyms of acid test include assessment.

acid test (noun)	appraisal (noun)
a rigorous or crucial appraisal	an expert estimation of the quality, quantity, and other characteristics of someone or something
	the classification of someone or something with respect to its worth
	a document appraising the value of something (as for insurance or taxation)